Dynamic delay equalization for media transport

ABSTRACT

Systems and methods of the present disclosure provide for dynamic delay equalization of related media signals in a media transport system. Methods include receiving a plurality of related media signals, transporting the related media signals along different media paths, calculating uncorrected propagation delays for the media paths, and delaying each of the related media signals by an amount related to the difference between the longest propagation delay (of the uncorrected propagation delays) and the uncorrected propagation delay of the related media signal/media path. Calculating the uncorrected propagation delays and delaying the related media signals may be performed in response to a change to the propagation delay of at least one of the related media signals/media paths. Additionally or alternatively, calculating the uncorrected propagation delays and delaying the related media signals may be performed while transporting the related media signals.

FIELD OF THE INVENTION

The present disclosure relates to dynamic delay equalization for mediatransport.

BACKGROUND OF THE INVENTION

When related audio and video content are rendered together (to beobserved at the same time), the audio and video signals need to be timealigned or the observer will recognize a lip sync' error. This error isnamed lip sync because observers are keenly aware of it when the sightof a person's lips does not match timing of the accompanying sound ofthe person's voice. Lip sync error is due to audio and video signalsbeing presented with different amounts of delay. The error is correctedby delaying the earlier signal (almost always the audio signal).

Lip sync error is a concern because video processing generally inducesdelays that are significantly longer than audio processing delays. Somestudies indicate observers will notice lip sync errors where the audioleads (is more advanced than) the video by more than 45 ms(milliseconds) and where the audio lags (trails) the video by more than125 ms. The recommendation of the ATSC (Advanced Television SystemsCommittee) Implementation Subcommittee IS-191 is to align related audioand video signals within the range of −15 ms (audio leads) to 45 ms(audio lags).

Further, audio signals that are rendered together may produce anoticeable delay or echo if not sufficiently time aligned. A humanobserver will hear two sounds separated by a sufficiently short delay asa single, fused auditory image (the Haas effect). The maximum delay(called the echo threshold) varies according to the type of sound andcircumstances, and may range from about 5-40 ms. Hence, audio signalsthat are rendered together may need a relative delay of less than about40 ms to achieve auditory fusion. Even below the threshold for audiofusion, comb filtering effects may be heard if the same audio signal isrendered by separate transducers that produce a relative delay of a fewmilliseconds or less.

SUMMARY OF THE INVENTION

Systems and methods of the present disclosure provide for dynamic delayequalization of related media signals in a media transport system.Methods include receiving a plurality of related media signals,transporting the related media signals along different media paths,calculating uncorrected propagation delays for the media paths, anddelaying each of the related media signals by an amount related to thedifference between the longest propagation delay (of the uncorrectedpropagation delays) and the uncorrected propagation delay of the relatedmedia signal/media path. The related media signals are each sourced froma shared source space and are destined to a shared observation space.Calculating the uncorrected propagation delays and delaying the relatedmedia signals may be performed in response to a change to thepropagation delay of at least one of the related media signals/mediapaths. Additionally or alternatively, calculating the uncorrectedpropagation delays and delaying the related media signals may beperformed while transporting the related media signals.

Systems include edge input devices and edge output devices to receiveand transmit media signals. The edge input devices and the edge outputdevices are configured to transport the media signals along media pathsbetween the edge input devices and the edge output devices. The mediapaths have dynamic delay elements to delay the media signals on command.The edge input devices are configured to transmit upstream delay signals(that characterize the propagation delays encountered by the mediasignals) to the edge output devices. The edge output devices areconfigured to determine uncorrected propagation delays of the mediasignals in the media paths. The edge output devices are configured toexchange information relating to the uncorrected propagation delays tosettle on a target propagation delay for all media signals (e.g., amaximum of the uncorrected propagation delays) and are configured tocommand the dynamic delay elements to delay the individual media signalsaccording to the difference between the target propagation delay and theindividual media signal uncorrected propagation delay.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a media transport system of thepresent disclosure.

FIG. 2 is a schematic representation of several media paths in a mediatransport system of the present disclosure.

FIG. 3 is a schematic representation of methods for dynamic delayequalization according to the present disclosure.

FIG. 4 is a schematic representation of computerized systems accordingto the present disclosure.

DETAILED DESCRIPTION OF INVENTION

For generalized sets of media signals (which each individually mayinclude an audio signal and/or a video signal), lip sync errorcorrection may be referred to as delay equalization, synchronizationand/or time alignment. For example, delay equalization may includeadding a delay to all but the slowest media signal so that all mediasignals may be presented substantially aligned in time, withoutsignificant synchronization error. Significant error is defined by humanperception of the error. Hence, delay equalization may require knowledgeor estimation of the difference in the total propagation delay of anaudio or video signal and the total propagation delay of a related audioor video signal to an accuracy of better than about 50 ms (.+−.50 ms).In some embodiments, the accuracy is better than 20 ms, better than 10ms, better than 1 ms, better than 0.1 ms, or better than 0.01 ms. Thesystems and methods of the present disclosure may be configured to alignrelated audio signals and video signals to better than 50 ms, betterthan 10 ms, or better than 1 ms. The systems and methods of the presentdisclosure may be configured to align related audio signals to betterthan 10 ms, better than 1 ms, better than 0.1 ms, or better than 0.01ms. Groups of signals, such as all audio signals or stereo audiosignals, may be independently aligned and then the group aligned withother groups or other individual signals.

Audio delays may be known or estimable at the time of systemconfiguration and/or system design due to the nature of the audioprocessing (generally small and similar delays). For example, all thedelays of processing and transport may be known, characterized, and/orselected before and/or during system design and/or system configuration.However, some delays, such as due to video processing, variable lengthaudio processing, and network transport, may vary significantlyaccording to the signal source, the type of processing applied, and/orthe network architecture. Where the delays of all media signals areknown or estimable at the time of configuration and/or design, delayequalization may be called static delay equalization. Where at leastsome of the delays may vary or change at run time (during the operationof the media transport system rather than during the configurationand/or design of the media transport system), delay equalization may becalled dynamic delay equalization.

In dynamic delay equalization systems and methods of the presentdisclosure, related media signals may be synchronized at run time bytracking the total propagation delay of related media signals at runtime and applying an individualized delay to all but the slowest(longest propagation delay) of related media signals. Generally, relatedmedia signals include at least one audio signal and at least one videosignal. Dynamic delay equalization according to the present disclosuremay be referred to as automatic dynamic delay equalization because thesystems and methods of the present disclosure provide a mechanism toprovide dynamic delay equalization with little to no user interventionneeded (e.g., during the operation of the system or method).

As used herein, media signals are signals (generally digital signals)conveying media information. The media information may be audio(possibly including multiple audio channels, e.g., stereo, surroundsound, etc.), video, audio and video, and/or associated data (e.g.,closed captioning, time codes, etc.). The source of a media signal maybe a transducer such as a camera, a microphone, etc. that produces amedia signal representative of the physical environment. The source of amedia signal may be a receiver and/or a decoder which accepts anelectronic input and emits the media signal (e.g., a media server, anaudio receiver, a video receiver, an audio-video receiver, and astreaming media device). The media signal may be conveyed using adigital communication protocol and/or interface (e.g., HDMI(High-Definition Multimedia Interface), SDI (Serial Digital Interface),DisplayPort, USB (Universal Serial Bus), FireWire (IEEE 1394), IP(Internet Protocol), UDP (User Datagram Protocol), TCP (TransmissionControl Protocol), RTP (Real-time Transport Protocol), AES67 (AudioEngineering Society), AVB (Audio Video Bridging), and AVB/TSN (AudioVideo Bridging/Time-Sensitive Networking)), The media signal may bepropagated as a media stream or other form of continuous orquasi-continuous data stream. A media stream and a data stream are notnecessarily data sourced or transmitted over an Internet, Ethernet, orother network connection.

Media signals are related if they have the same origin and the samedestination. Media signals with the same origin originate in the samephysical space, same context, and/or same device. For example, mediasignals delivered as a combined signal from a source such as a mediaplayer, video server, satellite receiver, etc. are media signals withthe same origin. Media signals generated by microphones and cameras thatare observing the same event are media signals with the same origin.Embedded audio with video from a video media player source (DVD,satellite receiver, etc.) are media signals with the same origin. Asused herein, the common origin of related media signals is referred toas a shared source space and may be referred to as a shared acquisitionspace, a unified source space, a shared timing context, and a unifiedtiming context. Media signals with the same destination are rendered in,or affect audio and/or video rendered in, the same physical space, samecontext, or same device. For example, a video signal displayed on ascreen and an audio signal played by loudspeakers have the samedestination if the video on the screen and the audio from theloudspeakers are simultaneously observable. Media signals that arecombined, transmitted and/or encoded together as an output signal and/orstream (e.g., as embedded audio and video, a multimedia file, etc.) havethe same destination. As used herein, the common destination of relatedmedia signals is referred to as a shared observation space and may bereferred to as a shared rendering space, a unified observation space, ashared rendering context, and a unified rendering context. Hence,related media signals are sourced from a shared source space and arerendered in a shared observation space.

FIGS. 1-4 illustrate systems and methods of dynamic delay equalizationfor media transport. In general, in the drawings, elements that arelikely to be included in a given embodiment are illustrated in solidlines, while elements that are optional or alternatives are illustratedin dashed lines. However, elements that are illustrated in solid linesare not essential to all embodiments of the present disclosure, and anelement shown in solid lines may be omitted from a particular embodimentwithout departing from the scope of the present disclosure. Elementsthat serve a similar, or at least substantially similar, purpose arelabelled with numbers consistent among the figures. Like numbers in eachof the figures, and the corresponding elements, may not be discussed indetail herein with reference to each of the figures. Similarly, allelements may not be labelled or shown in each of the figures, butreference numerals associated therewith may be used for consistency.Elements, components, and/or features that are discussed with referenceto one or more of the figures may be included in and/or used with any ofthe figures without departing from the scope of the present disclosure.

FIG. 1 is a schematic representation of a media transport system 10 thatincludes at least two distinct media paths 16 to transport at least twodistinct media signals 12 from a shared source space 26 to a sharedobservation space 28. Because the media signals 12 originate in theshared source space 26 and are destined to the shared observation space28, the media signals 12 may be referred to as related media signals.Each media path 16 includes an edge input device 30 at an ingress 14 tothe media path and an edge output device 34 at an egress 24 to the mediapath. Though the example of FIG. 1 illustrates just two media paths 16(a first media path 18 and a second media path 20), the media transportsystem 10 may include a multitude of media paths 16 between the sharedsource space 26 and the shared observation space 28. The number of mediapaths 16 may be configurable in hardware and/or in software. The mediatransport system 10 may permit a user to specify the shared source space26, the shared observation space 28, which media signals are related,which media paths carry related media signals 12, which edge deviceshave an ingress in the shared source space 26, and/or which edge deviceshave an egress in the shared observation space 28.

Ingresses 14 and egresses 24 are physical and/or logical connectionsto/from the media paths 16 that permit the media signals 12 toenter/exit the media paths 16. Media paths 16 may have multipleingresses 14 for different media signals 12 to be input to one mediapath 16. Additionally or alternatively, one ingress 14 may acceptmultiple media signals 12. Media paths 16 may have multiple egresses 24for different media signals 12 to be output from one media path 16.Additionally or alternatively, one egress 24 may emit multiple mediasignals 12. Each edge input device 30 presents at least one ingress 14to at least one media path 16. Each edge output device 34 presents atleast one egress 24 from at least one media path 16.

The edge input devices 30 are configured to receive the associated mediasignal 12 from the shared source space 26 through the associated ingress14. The associated media signal may originate as video and embeddedaudio in an audio-visual signal, e.g., from a video media file, DVD,video media player, etc. The associated media signal may originate fromsensors such as cameras and/or microphones observing the same event.Each individual media signal 12 (audio or video signal) is received byan edge input device 30. A single edge input device 30 may receive morethan one media signal 12 and/or more than one type of media signal 12(e.g., audio signal, video signal, embedded audio and video signal).

The edge output devices 34 are configured to receive the associatedmedia signal 12 from the respective edge input device 30. The associatedmedia signal 12 may be transmitted directly or indirectly between theedge input device 30 and the edge output device 34. For example, themedia path 16 may include one or more intermediate devices 38 betweenthe edge input device 30 and the edge output device 34. As anotherexample, the media signal 12 may be transported through a network fabric64 as discussed further herein.

During transport between the ingress 14 and the egress 24 (e.g., throughthe edge input device 30, through the edge output device 34, and betweenthe edge devices), the media signal 12 experiences propagation delay. Asused herein, propagation delay includes processing and transport delays.

At least one media signal 12 is transported through a different mediapath 16 than another of the media signals 12. Generally, each mediasignal 12 passes through a different media path 16 from the ingress(es)14 to the egress(es) 24, even if more than one media signal 12 passesthrough the same device or devices along the path from one ingress 14 toone egress 24. Media paths 16 are distinct if there is some differencebetween the media paths. For example, media paths 16 are distinct if atleast one of: the edge input devices 30 are different, the edge outputdevices 34 are different, one or more intermediate devices 38 aredifferent, or processing within one or more of the devices is different.Generally, the media signals 12 in distinct media paths 16 experiencedifferent propagation delays (without including the effects of dynamicdelay equalization).

The edge output devices 34 also are configured to receive an upstreamdelay signal 36 from the upstream device or devices. The upstream delaysignal 36 is related to the propagation delay experienced by the mediasignal 12 as it passes through the edge input device 30, intermediatedevices 38, and/or network or other transport. The upstream delay signal36 may indicate a delay time, a latency, and/or a timestamp. Delaytimes, latencies, and/or timestamps may be absolute (from beginning toend of the period measured) or relative to a given event, given time,and/or a given media signal. Delay times, latencies, and timestamps eachindependently may be represented as a time value and/or a number ofcycles of a clock.

At least the edge input device 30 within a media path 16 is configuredto estimate and/or to determine the propagation delay (processing andtransport delays) experienced by the media signal 12 as it passesthrough the edge input device 30. The edge output device 34 isconfigured to receive the propagation delay (or a value related to thepropagation delay) from the edge input device 30 (directly or viaintermediaries such as the network or intermediate devices 38).Additionally or alternatively, intermediate devices 38 may be configuredto receive the upstream delay signal 36 from the edge input device 30 orother intermediate devices 38 and to modify the upstream delay signal 36by adding the subject intermediate device's propagation delay (asestimated or determined) to the propagation delay of the upstream deviceor devices. Each device which adds a propagation delay to the upstreamdelay signal 36 also may add an estimate or determination of thepropagation delay between the origin of the upstream delay signal andthe subject device. Hence, the upstream delay signal 36 communicates anestimate and/or determination of the total propagation delay of themedia signal 12 up to the point of transmission from the device thattransmits the upstream delay signal.

In the example of FIG. 1, the upstream delay signals 36 are shown aspropagating in an independent channel between devices. Any or all of theupstream delay signals 36 may be transmitted in the same medium, in thesame channel, and/or in the same port as the media signal 12. Generally,edge input devices 30 and intermediate devices 38 that transmit anupstream delay signal 36 provide an upstream delay signal for each ofthe media signals 12 that the respective device handles.

The edge output devices 34 also are configured to determine anuncorrected propagation delay from the ingress 14 to the egress 24 basedupon the upstream delay signal 36 (which communicates the upstreamdelay). The uncorrected propagation delay generally does not includedynamic delay (as described further herein) imposed by the mediatransport system 10 to time align the media signals 12. The uncorrectedpropagation delay also may be based upon an estimate and/ordetermination of the propagation delay of the media signal 12 throughthe edge output device 34 and/or the propagation delay of the mediasignal to the point of rendering in the shared observation space 28.Hence, the uncorrected propagation delay may incorporate the estimated,known, or otherwise determined propagation delays of the media signal 12from the ingress 14 to the egress 24 and/or to the final point ofpresentation of the media signal. Propagation delays after the egress 24may include transport delays and media processing delays (e.g., videoprocessing delays) for the device that renders the media signal (e.g., avideo display).

The media signal 12 may be transported through a network fabric 64 ofthe media transport system 10. The network fabric 64 may have a fixed ordynamic topology. For example, the network fabric 64 may be a network ofdirect cables connecting the various devices of the media transportsystem 10. As another example, the network fabric 64 may include, and/ormay be, an AVB network (e.g., an AVB/TSN network), a CobraNet network,and/or an AES67 network.

Each media path 16 includes a dynamic delay element 40 configured todelay the media signal 12 based upon a delay command communicated by adelay signal 42. The dynamic delay element 40 may be a buffer, repeater,etc. The variable delay introduced by the dynamic delay element 40generally is not reflected in the uncorrected propagation delaydetermined by the edge output device 34. Static delay, delay notaffected by the delay signal 42, may be reflected in the uncorrectedpropagation delay. Media paths 16 may include multiple dynamic delayelements 40, in which case the total delay applied to each media signal12 may be distributed among the dynamic delay elements 40 of the mediapath 16. Dynamic delay elements 40 may be independent programmable delayelements in the media path 16 and/or may be incorporated into the edgeinput device 30, the edge output device 34, and/or one or more of theintermediate devices 38.

Edge output devices 34 are configured to exchange a delay coordinationsignal 44 relating to the uncorrected propagation delays determined byeach of the edge output devices 34. For example, each edge output device34 may provide its uncorrected propagation delay to each of the otheredge output device 34. Hence, each edge output device 34 may have accessto all of the uncorrected propagation delays. Additionally oralternatively, the media transport system 10 may include a dynamic delayagent 60 which may receive the uncorrected propagation delays from eachof the edge output devices 34 (via the delay coordination signals 44).The dynamic delay agent 60 is a process and/or device of the mediatransport system 10. The dynamic delay agent 60 may be implemented as anagent, a broker, a central authority, a daemon, a service, etc.

The dynamic delay agent 60, at least one of the edge output devices 34,and/or each of the edge output devices 34 may calculate the maximum ofthe uncorrected propagation delays (which may be referred to as thelongest propagation delay and the target propagation delay). That is,the edge output devices 34 utilize the delay coordination signal 44(directly or indirectly via the dynamic delay agent 60) to settle on thelongest (target) propagation delay. The dynamic delay agent 60 or one ofthe edge output devices 34 may establish the longest propagation delayand distribute the value to the remaining edge output devices 34.Additionally or alternatively, each of the edge output devices 34 maycalculate the longest propagation delay using the same method (thevalues may or may not be exchanged or otherwise distributed among theedge output devices 34).

The difference between the longest propagation delay and the uncorrectedpropagation delay of each media signal 12 may be applied to therespective dynamic delay elements 40 to cause each of the media signalsexcept the longest delayed media signal to be delayed a total delay thatmatches the longest propagation delay. Where the delay to be applied isless than a threshold (e.g., less than 50 ms, 20 ms, 10 ms, 1 ms, 0.1ms, or 0.01 ms), the delay may not be communicated to the dynamic delayelement 40 and/or the dynamic delay element 40 may not apply the delay.The delay to be applied by each dynamic delay element 40 may becommunicated by the dynamic delay agent 60 and/or the edge outputdevices 34 to the dynamic delay elements (via delay signal 42). Each ofthe edge output devices 34 may receive the longest propagation delayand/or the difference between the longest propagation delay and theuncorrected propagation delay of that edge output device 34.

If any of the elements of a media path 16 changes propagation delay(e.g., by changing processing, source, and/or transport), the upstreamdelay signal 36 communicates the revised delay to the downstreamelements until received and used by the edge output device 34 of themedia path 16. The edge output device 34 may then calculate a reviseduncorrected propagation delay that may affect the delays applied to eachof the media paths. If the revised uncorrected propagation delay is lessthan the longest propagation delay, the delay applied (via the dynamicdelay element 40) to the media path of the revised uncorrectedpropagation delay is affected. If the revised uncorrected propagationdelay is greater than the longest propagation delay, the delays appliedto all media paths 16 may be affected. If the prior value of theuncorrected propagation delay was the longest propagation delay, thedelays applied to all media paths 16 may be affected.

Thus, all related media signals 12 may be time aligned (synchronized).The related media signals 12 generally are aligned at the egresses 24and/or in the shared observation space 28. Media signals 12 additionallymay be aligned at one or more processing or transport boundaries withinthe media transport system 10. However, compensating for the propagationdelays of each media signal 12 only once between the shared source space26 and the shared observation space 28 permits a total latency of therelated media signals 12 that is substantially the same as the totalpropagation delay experienced by the longest delayed media signal(without any dynamic delay applied). Using intermediate points for timealignment may result in additional delays applied to all media signalsand hence an increased total latency.

The media transport system 10 may include facility for other mediasignals and other media paths that are not connected to the sharedsource space 26 and the shared observation space 28. The media transportsystem 10 may time align the other media signals independent of or inconjunction with the related media signals 12. Additionally oralternatively, the media transport system 10 may apply static delayequalization (i.e., delays that do not change at run time) to therelated media signals 12 and/or to the other media signals. In staticdelay equalization, the media transport system 10 may estimate,determine, or otherwise identify the delay (static delays) each mediasignal would need to be time aligned (omitting run-time variabledelays). Further, the media transport system 10 may apply the staticdelays to each affected media signal. For related media signals 12, thestatic delays may be embedded in dynamic delay elements 40 as a minimumdelay.

When integrating a static delay equalization scheme and a dynamic delayequalization scheme, using timestamps to define the static and dynamicdelays may be convenient. Additionally or alternatively, static anddynamic delays may be expressed as latencies and/or delay times.

FIG. 2 illustrates a media transport system 10 with several media pathsthat each may be affected by static delay equalization and dynamic delayequalization. Media paths between the shared source space 26 and theshared observation space 28 may include the path from Device-1 (an edgeinput device 30) to Device-5 (an edge output device 34), the direct pathfrom Device-2 (an edge input device 30) to Device-5, the indirect pathfrom Device-2 to Device-5 (through Device-4, an intermediate device 38),the path from Device-2 to Device-6 (an edge output device 34), the pathfrom Device-3 (an edge input device 30) to Device-5, and the path fromDevice-3 to Device-6. The media paths may pass through a multiplexer 58(a device which may switch and/or replicate the media signal 12). InFIG. 2, propagation delay and timestamp values generally increase fromleft to right.

In the example of FIG. 2, upstream delay signals are configured suchthat the downstream devices (such as Device-4, Device-5, and Device-6)may receive the upstream delay signal 36 from the upstream device ordevices in the same media path. Each of the edge input devices 30 andthe intermediate devices 38 may provide an upstream delay signal thatcommunicates a timestamp associated with the output of the device. Forexample, in the media path of Device-1 to Device-5, Device-1 maycalculate and provide a timestamp reflecting the propagation delay ofthe transported media signal. Device-1 may communicate the timestamp toDevice-5 through a variety of mechanisms (e.g., direct signal,broadcast, inter-process communication, event-driven communication,etc.). For example, Device-1 may provide the timestamp as a subscribableelement and Device-5 may subscribe to the element. When Device-1 changesits timestamp, subscribed devices (such as Device-5) receive theupstream delay signal to report the revised timestamp. Each of Device-2,Device-3, and Device-4 may provide a timestamp in the same manner asdescribed and/or as each other. Each of Device-4, Device-5, and Device-6may receive a timestamp in the same manner as described and/or as eachother.

Each device that receives the timestamp (an incoming timestamp) from oneof the downstream devices (i.e., Device-4, Device-5, and Device-6) maydetermine the timestamp at its output by adding an estimate ordetermination of the network latency between the devices and adding anestimate or determination of the internal propagation delay of thereceiving device to the incoming timestamp. In this manner, each edgeoutput device 34 may determine an independent value for the uncorrectedpropagation delay of the media signal that is output. Edge input devices30 and/or intermediate devices 38 may not have any indication of theuncorrected propagation delay of any of the media signals, including themedia signal passing through the device. Because the timestamps arepropagated downstream, a change in the processing and/or transport(resulting in a change in propagation time) of a media signal by anupstream device may be communicated to downstream devices, which may acton the change by calculating revised uncorrected propagation delays.

In the example of FIG. 2, Device-2 and Device-3 are subject to staticdelay equalization, as indicated by the source offsets 54 of theirinputs relative to the timestamp at the edge of the shared source space26. For example, Device-3 and Device-6 may be audio only devices withpropagation delays that do not vary substantially according to input ortype of processing. For devices that have a source offset 54 due tostatic delays (e.g., Device-2 and Device-3), the source offset may beincorporated in the timestamp of the device and/or the source offset maybe communicated to the edge output device 34 at the end of the mediapath (e.g., Device-5 and/or Device-6).

During configuration, the media transport system 10 may insert dynamicdelay elements 40 before each edge output device 34 (for each mediasignal 12 that is input to the device) such that each media signalencounters at least one dynamic delay element. For example, dynamicdelay elements 40 that are directly upstream of edge output devices 34in the example of FIG. 2 are DD5 a, DD5 b, DD5 c, and DD6. The mediatransport system 10 may insert dynamic delay elements 40 after one ormore upstream devices such as edge input devices 30 and intermediatedevices 38. For example, dynamic delay elements 40 that are directlydownstream of other devices in the example of FIG. 2 are DD3 and DD4.For media paths that include more than one dynamic delay element 40, thetotal added delay may be distributed among the dynamic delay elements.Additionally or alternatively, one dynamic delay element 40 may affectthe propagation delay of a media signal that may be routed through morethan one edge output device 34. For example, the dynamic delay elementsDD3 and DD4 may affect the media signals that are routed to Device-5and/or Device-6 through the multiplexer 58.

FIG. 3 schematically represents methods 100 for dynamic delayequalization of media signals (dynamic time alignment) in a mediatransport system such as media transport system 10. Methods 100 includereceiving 102 related media signals, transporting 104 the related mediasignals, calculating 106 the uncorrected propagation delays (D.sub.i),calculating 108 the longest propagation delay (D.sub.max), and delaying110 each media signal according to the difference between the longestpropagation delay and the respective uncorrected propagation delay(D.sub.max-D.sub.i). Generally, the calculating 106 the uncorrectedpropagation delays, calculating 108 the longest propagation delay, anddelaying 110 each media signal is performed while transporting 104.Thus, changes in the propagation delays of the individual media signalsmay be used to maintain the media signals in time alignment during runtime of the media transport system.

Receiving 102 includes receiving at least two related media signals andmay include receiving a plurality of media signals. The related mediasignals all have an origin in a shared source space. Receiving 102 mayinclude receiving each of the media signals at a different ingress ofedge input devices of the media transport system. The related mediasignals all have a destination in a shared observation space.

Transporting 104 includes transporting the related media signals alongdifferent media paths. That is, at least one media signal is routedalong a media path that is different than at least one other media pathof the other media signals. Transporting 104 may include transportingeach of the media signals to a different egress of edge output devicesof the media transport system. Transporting 104 additionally may includetransmitting each of the media signals at the respective egresses of themedia transport system. Transporting 104 may include transporting themedia signals across a network fabric (such as an AVB network) thatinterconnects ingresses and egresses of the media transport system.

Transporting 104 may induce propagation delays in each of the mediasignals. Transporting 104 may include transporting the media signals toand/or from processing devices (e.g., edge input device 30, edge outputdevice 34, and intermediate device 38). Additionally or alternatively,transporting 104 may include processing the media signals. The result oftransporting 104 and/or processing within the media transport system isthat the related media signals experience different propagation delays(before delaying 110). That is, at least one media signal experiences adifferent propagation delay than at least one other media signal.

Calculating 106 includes calculating the uncorrected propagation delays(D.sub.i) of each of the media signals due to the individual media pathstaken by each media signal. Calculating 106 may include estimatingand/or determining the propagation delay due to each processing andtransport element within the respective media path of each media signal.

Calculating 106 may include estimating and/or determining thepropagation delay of each media signal within the shared observationspace. Edge input devices may calculate a propagation delay of thecorresponding media signal due to the effect of the edge input deviceand/or upstream effects. The edge input devices may communicate thepropagation delay to downstream devices. Downstream devices maycalculate a propagation delay of the media signal due to the effect ofthe subject device and/or upstream effects such as the propagation delaycommunicated by the edge input device and/or propagation delay inducedby transport. Each intermediate device may add its propagation delay tothe propagation delay communicated by upstream devices and communicatethe resultant accumulated delay to downstream devices. Hence, downstreamdevices may receive an upstream delay signal that includes thepropagation delay of upstream devices and/or transport between thedevices. The edge output device may calculate the uncorrectedpropagation delay based on the accumulated upstream propagation delay(and/or the upstream propagation delays of the upstream devices and/ortransport between the devices) and an estimate or determination of theedge output device's propagation delay. Each edge output device mayindependently calculate an uncorrected propagation delay of the mediasignal handled by that edge output device.

Calculating 108 includes calculating the maximum value of theuncorrected propagation delays (D.sub.i). The maximum value is thelongest propagation delay (D.sub.max). Edge output devices maycommunicate to each other the uncorrected propagation delay of the mediasignals calculated by the individual edge output devices. Edge outputdevices may each independently calculate the longest delay independentlybased on the uncorrected propagation delays of all of the media signals.Additionally or alternatively, the media transport system may include adynamic delay agent which calculates the longest propagation delay.

Delaying 110 includes delaying each media signal such that all mediasignals have total propagation delays (including the uncorrectedpropagation delay and the effects of delaying 110) that aresubstantially the same (e.g., within human perception). For example, therange of propagation delays of the media signals (the difference fromthe maximum to the minimum) may be less than 100 ms, less than 40 ms,less than 20 ms, less than 10 ms, less than 2 ms, less than 1 ms, lessthan 0.2 ms, less than 0.05 ms, less than 0.02 ms, or less than 0.01 ms.Alternatively expressed, creating a particular range of propagationdelays of the media signals may be described as time aligning (orsynchronizing) the media signal to within the particular range. Formixed audio and video signals, the absolute difference between theaverage propagation delays of the video signals and the averagepropagation delays of the audio signals may be less than 100 ms, lessthan 40 ms, less than 20 ms, less than 10 ms, less than 2 ms, or lessthan 1 ms. Audio and video media signals should be aligned sufficient toavoid the perception of lip sync errors by an observer observing bothtypes of media signals. For audio media signals (e.g., the entire groupof media signals or a portion of a mixed group of media signals), therange of propagation delays of the audio signals may be less than 40 ms,less than 20 ms, less than 10 ms, less than 2 ms, less than 1 ms, lessthan 0.2 ms, less than 0.05 ms, less than 0.02 ms, or less than 0.01 ms.Audio media signals may be aligned sufficient to achieve auditory fusionin an observer observing the audio media signals. Audio media signalsmay be aligned to within a few digital sampling cycles of the audiomedia signals (e.g., within 4 cycles, within 2 cycles, or within 1 cycleof 48 kHz sampled audio media signals).

The media signal with the longest propagation delay may not beadditionally delayed by delaying 110. The delay applied to each mediasignal by the delaying 110 may be the difference between the longestdelay and the media signal's uncorrected propagation delay(D.sub.max-D.sub.i). This difference is zero for the media signal withthe longest propagation delay. All other media signals are delayed bythe delaying 110. Delaying 110 may include delaying each media signal bya uniform amount greater than D.sub.max-D.sub.i.

Delaying 110 may include inserting dynamic delay elements and/orapplying dynamic delay elements within the media paths of all but thelongest delayed media path (or all media paths). The dynamic delayelements may be dynamic delay elements 40.

FIG. 4 schematically represents a computerized system 200 that may beused to implement and/or instantiate media transport system 10 andcomponents thereof, such as edge input device 30, edge output device 34,intermediate device 38, and dynamic delay element 40. The computerizedsystem 200 includes a processing unit 202 that may be operativelycoupled to a computer-readable memory 206 by a communicationsinfrastructure 210. The processing unit 202 may include one or morecomputer processors 204 and may include a distributed group of computerprocessors 204. The processing unit 202 may include, or be implementedon, programmable, reconfigurable, and/or dedicated hardware such asfield-programmable gate arrays, digital signal processors, and/orapplication specific integrated circuits.

The computerized system 200 also may include a computer-readable storagemedia assemblage 212 that is operatively coupled to the processing unit202 and/or the computer-readable memory 206, e.g., by communicationsinfrastructure 210. The computer-readable storage media assemblage 212may include one or more non-transitory computer-readable storage media214 and may include a distributed group of non-transitorycomputer-readable storage media 214.

The communications infrastructure 210 may include a local data bus, acommunication interface, and/or a network interface. The communicationsinfrastructure 210 may be configured to transmit and/or to receivesignals, such as electrical, electromagnetic, optical, and/or acousticsignals. The communication infrastructure 210 may include the ingress 14and/or the egress 24.

The computerized system 200 may include one or more input-output devices216 operatively coupled to the processing unit 202, thecomputer-readable memory 206, and/or the computer-readable storage mediaassemblage 212. Input-output devices 216 are generally configured foruser interaction and may be configured for visual, audio, and/or tactileinput and/or output. Each input-output device 216 independently may beconfigured for only input, only output, primarily input, primarilyoutput, and/or a combination of input and output. Examples ofinput-output devices 216 include monitors (e.g., video monitor),displays (e.g., alphanumeric displays, lamps, and/or LEDs), keyboards,pointing devices (e.g., mice), touch screens, speakers, and buzzers.

The computerized system 200 may include a distributed group ofcomputers, servers, workstations, etc., which each may be interconnecteddirectly or indirectly (including by network connection). Thus, thecomputerized system 200 may include one or more processing units 202,computer-readable memories 206, computer-readable storage mediaassemblages 212, and/or input-output devices 216 that are locatedremotely from one another.

One or both of the computer-readable memory 206 and thecomputer-readable storage media assemblage 212 include control logic 220and/or data 222. Control logic 220 (which may also be referred to assoftware, firmware, gateware, and/or hardware) may include instructionsthat, when executed by the processing unit 202, cause the computerizedsystem 200 to perform one or more of the methods described herein.Control logic 220 may include one or more of the dynamic delay element40 and the dynamic delay agent 60. Data 222 may include the mediasignals, the propagation delay values, the longest propagation delay,and/or data associated with the methods described herein.

Where devices, elements, and/or methods are described as performing oneor more functions, the respective device and/or element is configured,e.g., programmed, to perform the function(s). The respective deviceand/or element may include one or more programs, agents, services,and/or components configured, e.g., programmed, to perform thefunction(s) when the programs, agents, services, and/or components areexecuted by the processing unit 202 or otherwise operated by thecomputerized system 200. The control logic 220 and/or data 222 mayinclude instructions and/or information corresponding to the programs,agents, services, and/or components.

Examples of inventive subject matter according to the present disclosureare described in the following enumerated paragraphs.

A1. A method for dynamic delay equalization of media signals in a mediatransport system, the method comprising:

receiving a first media signal at a first ingress of a media transportsystem and transporting the first media signal along a first media pathin the media transport system to a first egress of the media transportsystem;

receiving a second media signal at a second ingress of the mediatransport system and transporting the second media signal along a secondmedia path in the media transport system to a second egress of the mediatransport system, wherein the first media signal and the second mediasignal are sourced from a shared source space and are destined to ashared observation space;

calculating a first uncorrected propagation delay due to the first mediapath, calculating a second uncorrected propagation delay due to thesecond media path, and calculating a shortest propagation delay that isa shorter of the first uncorrected propagation delay and the seconduncorrected propagation delay;

delaying one of the first media signal and the second media signal thathas the shortest uncorrected propagation delay by an amount related to adifference between the first uncorrected propagation delay and thesecond uncorrected propagation delay;

in response to changed first media signal propagation parameters whiletransporting the second media signal, calculating a revised firstuncorrected propagation delay and calculating a revised shortestpropagation delay that is a shorter of the revised first uncorrectedpropagation delay and the second uncorrected propagation delay;

delaying one of the first media signal and the second media signal thathas the revised shortest uncorrected propagation delay by an amountrelated to a difference between the revised first uncorrectedpropagation delay and the second uncorrected propagation delay.

A2. The method of paragraph A1, wherein the receiving the first mediasignal includes receiving the first media signal with a first edge inputdevice of the media transport system at the first ingress of the mediatransport system and wherein the receiving the second media signalincludes receiving the second media signal with a second edge inputdevice of the media transport system at the second ingress of the mediatransport system.

A2.1. The method of paragraph A2, wherein the first edge input deviceinduces a first input propagation delay in the first media signal,wherein the calculating the first uncorrected propagation delay due tothe first media path includes calculating the first uncorrectedpropagation delay based on the first input propagation delay, whereinthe second edge input device induces a second input propagation delay inthe second media signal, and wherein the calculating the seconduncorrected propagation delay due to the second media path includescalculating the second uncorrected propagation delay based on the secondinput propagation delay.

A2.2. The method of any of paragraphs A2-A2.1, wherein the transportingthe first media signal includes transporting the first media signal fromthe first edge input device to a first edge output device of the mediatransport system at the first egress of the media transport system andwherein the transporting the second media signal includes transportingthe second media signal from the second edge input device to a secondedge output device of the media transport system at the second egress ofthe media transport system.

A2.2.1. The method of paragraph A2.2, wherein the first edge outputdevice induces a first output propagation delay in the first mediasignal, wherein the calculating the first uncorrected propagation delaydue to the first media path includes calculating the first uncorrectedpropagation delay based on the first output propagation delay, whereinthe second edge output device induces a second output propagation delayin the second media signal, and wherein the calculating the seconduncorrected propagation delay due to the second media path includescalculating the second uncorrected propagation delay based on the secondoutput propagation delay.

A2.2.2. The method of any of paragraphs A2.2-A2.2.1, wherein the firstedge input device induces a/the first input propagation delay in thefirst media signal, wherein the calculating the first uncorrectedpropagation delay due to the first media path includes receiving a firstupstream delay signal relating to the first input propagation delay atthe first edge output device, wherein the second edge input deviceinduces a/the second input propagation delay in the second media signal,and wherein the calculating the second uncorrected propagation delay dueto the second media path includes receiving a second upstream delaysignal relating to the second input propagation delay at the second edgeoutput device.

A2.2.3. The method of any of paragraphs A2.2-A2.2.2, wherein thecalculating the shortest propagation delay includes communicating thefirst uncorrected propagation delay from the first edge output device tothe second edge output device, communicating the second uncorrectedpropagation delay from the second edge output device to the first edgeoutput device, and calculating the shortest propagation delay in thefirst edge output device and in the second edge output device.

A3. The method of any of paragraphs A1-A2.2.3, wherein transporting thefirst media signal along the first media path includes transporting thefirst media signal along the first media path within a network fabric ofthe media transport system and wherein transporting the second mediasignal along the second media path includes transporting the secondmedia signal along the second media path within the network fabric, andoptionally wherein the network fabric includes an AVB (Audio VideoBridging) network.

A4. The method of any of paragraphs A1-A3, wherein the first mediasignal is a video signal and the second media signal is one of a videosignal and an audio signal.

A5. The method of any of paragraphs A1-A3, wherein the first mediasignal is an audio signal and the second media signal is an audiosignal.

A6. The method of any of paragraphs A1-A5, wherein the first ingress andthe second ingress are the same.

A7. The method of any of paragraphs A1-A6, wherein the first egress andthe second egress are the same.

A8. The method of any of paragraphs A1-A7, wherein the delaying one ofthe first media signal and the second media signal that has the shortestuncorrected propagation delay includes creating a relative propagationdelay of the first media signal and the second media signal that is lessthan 100 ms, less than 40 ms, less than 20 ms, less than 10 ms, lessthan 2 s, less than 1 ms, less than 0.2 ms, less than 0.05 ms, less than0.02 ms, or less than 0.01 ms.

A9. The method of any of paragraphs A1-A7, wherein the delaying one ofthe first media signal and the second media signal that has the revisedshortest uncorrected propagation delay includes creating a relativepropagation delay of the first media signal and the second media signalthat is less than 100 ms, less than 40 ms, less than 20 ms, less than 10ms, less than 2 ms, less than 1 ms, less than 0.2 ms, less than 0.05 ms,less than 0.02 ms, or less than 0.01 ms.

A10. The use of a media transport system to perform the method of any ofparagraphs A1-A9.

A11. A media transport system comprising:

a computer-readable memory;

a processing unit operatively coupled to the computer-readable memory;and

a computer-readable storage media assemblage, wherein thecomputer-readable storage media assemblage is operatively coupled to thecomputer-readable memory and includes instructions that, when executedby the processing unit, cause the system to perform the method of any ofparagraphs A1-A9.

B1. A method for dynamic delay equalization of related media signals ina media transport system, the method comprising:

(a) receiving a plurality of related media signals by a media transportsystem, wherein the related media signals are each sourced from a sharedsource space and are destined to a shared observation space;

(b) transporting the related media signals in the media transport systemalong different media paths;

(c) calculating an uncorrected propagation delay for each media path andcalculating a longest propagation delay that is a maximum of theuncorrected propagation delays;

(d) delaying each of the related media signals by an amount related to adifference between the longest propagation delay and the uncorrectedpropagation delay of that related media signal;

(e) in response to a change to a propagation delay of at least one ofthe related media signals while transporting the related media signals,determining a revised uncorrected propagation delay for each media pathand determining a revised longest propagation delay that is a maximum ofthe revised uncorrected propagation delays; and

(f) delaying each of the related media signals by an amount related to adifference between the revised longest propagation delay and the reviseduncorrected propagation delay of that related media signal.

B2. The method of paragraph B1, wherein determining the reviseduncorrected propagation delay for each media path includes calculatingthe revised uncorrected propagation delay of the related media signalsthat experienced the change.

B3. The method of any of paragraphs B1-B2, wherein the plurality ofrelated media signals includes a first media signal and a second mediasignal, and wherein the method includes the method of any of paragraphsA1-A9.

B4. The method of any of paragraphs B1-B3, wherein each media pathincludes an edge input device that induces an input propagation delayand an edge output device that induces an output propagation delay,wherein the (c) calculating the uncorrected propagation delay for eachmedia path includes calculating the uncorrected propagation delay basedupon the input propagation delay and the output propagation delay.

B4.1. The method of paragraph B4, further comprising communicating, foreach media path, the input propagation delay from the edge input deviceto the edge output device in parallel with the related media signal thatis transported along the media path, and optionally wherein the (c)calculating the uncorrected propagation delay for each media pathincludes calculating the uncorrected propagation delay by the edgeoutput device that receives the related media signal and the inputpropagation delay.

B4.2. The method of any of paragraphs B4-B4.1, wherein the (a) receivingthe plurality of related media signals includes receiving the pluralityof related media signals by the edge input devices of the media paths.

B4.3. The method of any of paragraphs B4-B4.2, wherein the (b)transporting the related media signals includes transporting the relatedmedia signals between the edge input devices and the edge output devicesof the media paths.

B4.4. The method of any of paragraphs B4-B4.3, further comprisingcommunicating an accumulated propagation delay for each related mediasignal and associated media path to the edge output device of the mediapath, and optionally wherein the (c) calculating the uncorrectedpropagation delay for each media path includes calculating, by the edgeoutput device that receives the related media signal and the accumulatedpropagation delay, the uncorrected propagation delay based on theaccumulated propagation delay.

B5. The method of any of paragraphs B1-B4.4, wherein the plurality ofrelated media signals includes at least one video media signal and atleast one audio media signal.

B6. The method of any of paragraphs B1-B5, wherein the plurality ofrelated media signals includes at least two audio media signals.

B7. The method of any of paragraphs B1-B6, wherein the (d) delayingincludes time aligning all of the related media signals to within 100ms, within 40 ms, within 20 ms, within 10 ms, within 2 ms, within 1 ms,within 0.2 ms, within 0.05 ms, within 0.02 ms, or within 0.01 ms.

B8. The method of any of paragraphs B1-B7, wherein the (d) delayingincludes time aligning all audio media signals of the related mediasignals to within 40 ms, within 20 ms, within 10 ms, within 2 ms, within1 ms, within 0.2 ms, within 0.05 ms, within 0.02 ms, or within 0.01 ms.

B9. The method of any of paragraphs B1-B8, wherein the (d) delayingincludes time aligning all audio media signals of the related mediasignals to all video media signals of the related media signals tocreate a range of propagation delays among the audio media signalsrelative to the video media signals that is less than 100 ms, less than40 ms, less than 20 ms, less than 10 ms, less than 2 ms, or less than 1ms.

B10. The method of any of paragraphs B1-B9, wherein the (f) delayingincludes time aligning all of the related media signals to within 100ms, within 40 ms, within 20 ms, within 10 ms, within 2 ms, within 1 ms,within 0.2 ms, within 0.05 ms, within 0.02 ms, or within 0.01 ms.

B11. The method of any of paragraphs B1-B10, wherein the (f) delayingincludes time aligning all audio media signals of the related mediasignals to within 40 ms, within 20 ms, within 10 ms, within 2 ms, within1 ms, within 0.2 ms, within 0.05 ms, within 0.02 ms, or within 0.01 ms.

B12. The method of any of paragraphs B1-B11, wherein the (f) delayingincludes time aligning all audio media signals of the related mediasignals to all video media signals of the related media signals tocreate a range of propagation delays among the audio media signalsrelative to the video media signals that is less than 100 ms, less than40 ms, less than 20 ms, less than 10 ms, less than 2 ms, or less than 1ms.

B13. The use of a media transport system to perform the method of any ofparagraphs B1-B12.

B14. A media transport system comprising:

a computer-readable memory;

a processing unit operatively coupled to the computer-readable memory;and a computer-readable storage media assemblage, wherein thecomputer-readable storage media assemblage is operatively coupled to thecomputer-readable memory and includes instructions that, when executedby the processing unit, cause the system to perform the method of any ofparagraphs B1-B12.

C1. A method for dynamic delay equalization of related media signals ina media transport system, the method comprising:

receiving a plurality of related media signals by a media transportsystem, wherein the related media signals are each sourced from a sharedsource space and are destined to a shared observation space;

transporting the related media signals in the media transport systemalong different media paths; and while transporting the related mediasignals: calculating an uncorrected propagation delay for each mediapath and calculating a longest propagation delay that is a maximum ofthe uncorrected propagation delays; and delaying each of the relatedmedia signals by an amount related to a difference between the longestpropagation delay and the uncorrected propagation delay of that relatedmedia signal.

C2. The method of paragraph C1, wherein a propagation delay of at leastone of the related media signals changes during transporting.

C3. The method of any of paragraphs C1-C2, wherein the plurality ofrelated media signals includes a first media signal and a second mediasignal, and wherein the method includes the method of any of paragraphsA1-A9.

C4. The method of any of paragraphs C1-C3, wherein each media pathincludes an edge input device that induces an input propagation delayand an edge output device that induces an output propagation delay,wherein the calculating the uncorrected propagation delay for each mediapath includes calculating the uncorrected propagation delay based uponthe input propagation delay and the output propagation delay.

C4.1. The method of paragraph C4, further comprising communicating, foreach media path, the input propagation delay from the edge input deviceto the edge output device in parallel with the related media signal thatis transported along the media path, and optionally wherein thecalculating the uncorrected propagation delay for each media pathincludes calculating the uncorrected propagation delay by the edgeoutput device that receives the related media signal and the inputpropagation delay.

C4.2. The method of any of paragraphs C4-C4.1, wherein the receiving theplurality of related media signals includes receiving the plurality ofrelated media signals by the edge input devices of the media paths.

C4.3. The method of any of paragraphs C4-C4.2, wherein the transportingthe related media signals includes transporting the related mediasignals between the edge input devices and the edge output devices ofthe media paths.

C4.4. The method of any of paragraphs C4-C4.3, further comprisingcommunicating an accumulated propagation delay for each related mediasignal and associated media path to the edge output device of the mediapath, and optionally wherein the calculating the uncorrected propagationdelay for each media path includes calculating, by the edge outputdevice that receives the related media signal and the accumulatedpropagation delay, the uncorrected propagation delay based on theaccumulated propagation delay.

C5. The method of any of paragraphs C1-C4.4, wherein the plurality ofrelated media signals includes at least one video media signal and atleast one audio media signal.

C6. The method of any of paragraphs C1-C5, wherein the plurality ofrelated media signals includes at least two audio media signals.

C7. The method of any of paragraphs C1-C6, wherein the delaying includestime aligning all of the related media signals to within 100 ms, within40 ms, within 20 ms, within 10 ms, within 2 ms, within 1 ms, within 0.2ms, within 0.05 ms, within 0.02 ms, or within 0.01 ms.

C8. The method of any of paragraphs C1-C7, wherein the delaying includestime aligning all audio media signals of the related media signals towithin 40 ms, within 20 ms, within 10 ms, within 2 ms, within 1 ms,within 0.2 ms, within 0.05 ms, within 0.02 ms, or within 0.01 ms.

C9. The method of any of paragraphs C1-C8, wherein the delaying includestime aligning all audio media signals of the related media signals toall video media signals of the related media signals to create a rangeof propagation delays among the audio media signals relative to thevideo media signals that is less than 100 ms, less than 40 ms, less than20 ms, less than 10 ms, less than 2 ms, or less than 1 ms.

C10. The use of a media transport system to perform the method of any ofparagraphs C1-C9.

C11. A media transport system comprising:

a computer-readable memory;

a processing unit operatively coupled to the computer-readable memory;and

a computer-readable storage media assemblage, wherein thecomputer-readable storage media assemblage is operatively coupled to thecomputer-readable memory and includes instructions that, when executedby the processing unit, cause the system to perform the method of any ofparagraphs C1-C9.

D1. A media transport system comprising:

a first media path that includes a first edge input device at a firstingress and a first edge output device at a first egress, wherein thefirst edge input device is configured to receive a first media signalfrom a shared source space, wherein the first edge output device isconfigured to receive the first media signal from the first edge inputdevice and to receive a first upstream delay signal from the first edgeinput device, wherein the first edge output device is configured totransmit the first media signal to a shared observation space, whereinthe first edge output device is configured to determine a firstuncorrected propagation delay from the first ingress to the first egressbased upon the first upstream delay signal, and wherein the first mediapath includes a first dynamic delay element configured to delay thefirst media signal based upon a first delay command;

a second media path that includes a second edge input device at a secondingress and a second edge output device at a second egress, wherein thesecond edge input device is configured to receive a second media signalfrom the shared source space, wherein the second edge output device isconfigured to receive the second media signal from the second edge inputdevice and to receive a second upstream delay signal from the secondedge input device, wherein the second edge output device is configuredto transmit the second media signal to the shared observation space,wherein the second edge output device is configured to determine asecond uncorrected propagation delay from the second ingress to thesecond egress based upon the second upstream delay signal, and whereinthe second media path includes a second dynamic delay element configuredto delay the second media signal based upon a second delay command;

wherein the first edge output device and the second edge output deviceare configured to exchange a delay coordination signal relating to thefirst uncorrected propagation delay and the second uncorrectedpropagation delay, and are configured to settle on a target propagationdelay that is at least as large as a maximum of the first uncorrectedpropagation delay and the second uncorrected propagation delay;

wherein the first edge output device is configured to command the firstdynamic delay element to delay the first media signal an amount of delayrelated to a difference between the first uncorrected propagation delayand the target propagation delay;

wherein the second edge output device is configured to command thesecond dynamic delay element to delay the second media signal an amountof delay related to a difference between the second uncorrectedpropagation delay and the target propagation delay.

D2. The media transport system of paragraph D1, wherein the mediatransport system includes a network fabric to interconnect the firstmedia path from the first edge input device to the first edge outputdevice and to interconnect the second media path from the second edgeinput device to the second edge output device, and optionally whereinthe network fabric includes an AVB (Audio Video Bridging) network.

D3. The media transport system of any of paragraphs D1-D2, wherein firstmedia signal is a video signal and the second media signal is one of avideo signal and an audio signal.

D4. The media transport system of any of paragraphs D1-D2, wherein thefirst media signal is an audio signal and the second media signal is anaudio signal.

D5. The media transport system of any of paragraphs D1-D4, wherein thefirst edge output device is configured to command the first dynamicdelay element to delay the first media signal an amount of delay relatedto a value by which the second uncorrected propagation delay exceeds thefirst uncorrected propagation delay.

D6. The media transport system of any of paragraphs D1-D5, wherein thesecond edge output device is configured to command the second dynamicdelay element to delay the second media signal an amount of delayrelated to a value by which the first uncorrected propagation delayexceeds the second uncorrected propagation delay.

D7. The media transport system of any of paragraphs D1-D6, wherein thefirst edge output device and the second edge output device areconfigured to exchange the first uncorrected propagation delay and thesecond uncorrected propagation delay, and optionally wherein each of thefirst edge output device and the second edge output device is configuredto determine the maximum of the first uncorrected propagation delay andthe second uncorrected propagation delay as the target propagationdelay.

D8. The media transport system of any of paragraphs D1-D6, wherein thefirst edge output device is configured to receive the second uncorrectedpropagation delay from the second edge output device, wherein the firstedge output device is configured to determine the maximum of the firstuncorrected propagation delay and the second uncorrected propagationdelay as the target propagation delay, and wherein the first edge outputdevice is configured to send the target propagation delay to the secondedge output device.

D9. The media transport system of any of paragraphs D1-D8, wherein thefirst edge output device is configured to command the first dynamicdelay element to delay the first media signal by a difference betweenthe target propagation delay and the first uncorrected propagationdelay.

D10. The media transport system of any of paragraphs D1-D9, wherein thesecond edge output device is configured to command the second dynamicdelay element to delay the second media signal by a difference betweenthe target propagation delay and the second uncorrected propagationdelay.

D11. The media transport system of any of paragraphs D1-D10, wherein themedia transport system includes a plurality of ingresses and a pluralityof egresses, is configured to receive a plurality of related mediasignals from the shared source space at the plurality of ingresses, andis configured to transmit the plurality of related media signals to theshared observation space from the plurality of egresses;

wherein the plurality of ingresses includes the first ingress and thesecond ingress, wherein the plurality of egresses includes the firstegress and the second egress, and wherein the plurality of related mediasignals includes the first media signal and the second media signal;

wherein each of the plurality of media signals has an uncorrectedpropagation delay and wherein the target propagation delay is a maximumof the uncorrected propagation delays of the plurality of related mediasignals.

D12. The media transport system of any of paragraphs D1-D11, wherein thefirst edge input device and the second edge input device are configuredto transmit the first media signal from the first egress and to transmitthe second media signal from the second egress with a relativepropagation delay of less than 100 ms, less than 40 ms, less than 20 ms,less than 10 ms, less than 2 ms, less than 1 ms, less than 0.2 ms, lessthan 0.05 ms, less than 0.02 ms, or less than 0.01 ms by commanding thefirst dynamic delay element and the second dynamic delay element.

D13. The use of the media transport system of any of paragraphs D1-D12to dynamically equalize delay between media signals, optionallyaccording to any of the methods of paragraphs A1-A9, B1-B12, or C1-C9.

As used herein, the terms “adapted” and “configured” mean that theelement, component, or other subject matter is designed and/or intendedto perform a given function. Thus, the use of the terms “adapted” and“configured” should not be construed to mean that a given element,component, or other subject matter is simply “capable of” performing agiven function but that the element, component, and/or other subjectmatter is specifically selected, created, implemented, utilized,programmed, and/or designed for the purpose of performing the function.It is also within the scope of the present disclosure that elements,components, and/or other recited subject matter that is recited as beingadapted to perform a particular function may additionally oralternatively be described as being configured to perform that function,and vice versa. Similarly, subject matter that is recited as beingconfigured to perform a particular function may additionally oralternatively be described as being operative to perform that function.

As used herein, the phrase, “for example,” the phrase, “as an example,”and/or simply the term “example,” when used with reference to one ormore components, features, details, structures, embodiments, and/ormethods according to the present disclosure, are intended to convey thatthe described component, feature, detail, structure, embodiment, and/ormethod is an illustrative, non-exclusive example of components,features, details, structures, embodiments, and/or methods according tothe present disclosure. Thus, the described component, feature, detail,structure, embodiment, and/or method is not intended to be limiting,required, or exclusive/exhaustive; and other components, features,details, structures, embodiments, and/or methods, including structurallyand/or functionally similar and/or equivalent components, features,details, structures, embodiments, and/or methods, are also within thescope of the present disclosure.

As used herein, the phrases “at least one of” and “one or more of,” inreference to a list of more than one entity, means any one or more ofthe entities in the list of entities, and is not limited to at least oneof each and every entity specifically listed within the list ofentities. For example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently, “at least one of A and/or B”)may refer to A alone, B alone, or the combination of A and B.

As used herein, the singular forms “a”, “an” and “the” may be intendedto include the plural forms as well, unless the context clearlyindicates otherwise.

In the event that any patents, patent applications, or other referencesare incorporated by reference herein and (1) define a term in a mannerthat is inconsistent with and/or (2) are otherwise inconsistent with,either the non-incorporated portion of the present disclosure or any ofthe other incorporated references, the non-incorporated portion of thepresent disclosure shall control, and the term or incorporateddisclosure therein shall only control with respect to the reference inwhich the term is defined and/or the incorporated disclosure was presentoriginally.

INDUSTRIAL APPLICABILITY

The systems and methods disclosed herein are applicable to thecommunication, entertainment, and video production industries.

The various disclosed elements of systems and steps of methods disclosedherein are not required of all systems and methods according to thepresent disclosure, and the present disclosure includes all novel andnon-obvious combinations and subcombinations of the various elements andsteps disclosed herein. Moreover, any of the various elements and steps,or any combination of the various elements and/or steps, disclosedherein may define independent inventive subject matter that is separateand apart from the whole of a disclosed system or method. Accordingly,such inventive subject matter is not required to be associated with thespecific systems and methods that are expressly disclosed herein, andsuch inventive subject matter may find utility in systems and/or methodsthat are not expressly disclosed herein.

It is believed that the following claims particularly point out certaincombinations and subcombinations that are directed to one of thedisclosed inventions and are novel and non-obvious. Inventions embodiedin other combinations and subcombinations of features, functions,elements and/or properties may be claimed through amendment of thepresent claims or presentation of new claims in this or a relatedapplication. Such amended or new claims, whether they are directed to adifferent invention or directed to the same invention, whetherdifferent, broader, narrower, or equal in scope to the original claims,are also regarded as included within the subject matter of theinventions of the present disclosure.

What is claimed is:
 1. A method, comprising: determining, by a mediatransport system, an uncorrected propagation delay for each media pathtransporting a plurality of related media signals; identifying, for eachmedia path, a maximum propagation delay as a propagation delay having alongest time period; delaying each related media signal, of theplurality of related media signals, by an amount determined bysubtracting the uncorrected propagation delay for each media path from acorresponding maximum propagation delay; identifying a reviseduncorrected propagation delay for each media path having a longest timeperiod; and delaying each related media signal, of the plurality of therelated media signals, by an amount determined by reducing the reviseduncorrected propagation delay for each media path from a correspondingrevised maximum propagation delay.
 2. The method of claim 1, whereineach media path includes an edge input device that induces an inputpropagation delay and an edge output device that induces an outputpropagation delay, wherein the determining the uncorrected propagationdelay for each media path includes determining the uncorrectedpropagation delay based upon the input propagation delay and the outputpropagation delay.
 3. The method of claim 2, further comprisingcommunicating, for each media path, the input propagation delay from theedge input device to the edge output device in parallel with the relatedmedia signal that is transported along the media path, and wherein thedetermining the uncorrected propagation delay for each media pathincludes determining the uncorrected propagation delay by the edgeoutput device that receives the related media signal and the inputpropagation delay.
 4. The method of claim 2, further comprisingcommunicating an accumulated propagation delay for each related mediasignal and associated media path to the edge output device of the mediapath, and wherein the determining the uncorrected propagation delay foreach media path includes determining, by the edge output device thatreceives the related media signal and the accumulated propagation delay,the uncorrected propagation delay based on the accumulated propagationdelay.
 5. The method of claim 2, further comprising communicating, foreach media path, the input propagation delay from the edge input deviceto the edge output device.
 6. The method of claim 2, further comprisingcommunicating, for each media path, the input propagation delay from theedge input device to the edge output device in parallel with the relatedmedia signal that is transported along the media path.
 7. The method ofclaim 2, further comprising communicating an accumulated propagationdelay for each related media signal and associated media path to theedge output device of the media path.
 8. The method of claim 7, whereinthe determining the uncorrected propagation delay for each media pathincludes determining the uncorrected propagation delay based on theaccumulated propagation delay.
 9. The method of claim 1, wherein thedelaying each include time aligning all of the related media signals towithin 20 ms.
 10. The method of claim 1, wherein the delaying eachinclude time aligning all audio media signals of the related mediasignals to within 2 ms.
 11. A method, comprising: determining, by amedia transport system, an uncorrected propagation delay for each mediapath carrying a plurality of related media signals; determining alongest propagation delay that is a maximum of the uncorrectedpropagation delays; and delaying each of the related media signals by anamount related to a difference between the longest propagation delay andthe uncorrected propagation delay of that related media signal.
 12. Themethod of claim 11, wherein each media path includes an edge inputdevice that induces an input propagation delay and an edge output devicethat induces an output propagation delay, wherein the determining theuncorrected propagation delay for each media path includes determiningthe uncorrected propagation delay based upon the input propagation delayand the output propagation delay.
 13. The method of claim 12, furthercomprising communicating, for each media path, the input propagationdelay from the edge input device to the edge output device in parallelwith the related media signal that is transported along the media path,and wherein the determining the uncorrected propagation delay for eachmedia path includes determining the uncorrected propagation delay by theedge output device that receives the related media signal and the inputpropagation delay.
 14. The method of claim 12, further comprisingcommunicating an accumulated propagation delay for each related mediasignal and associated media path to the edge output device of the mediapath, and wherein the determining the uncorrected propagation delay foreach media path includes determining, by the edge output device thatreceives the related media signal and the accumulated propagation delay,the uncorrected propagation delay based on the accumulated propagationdelay.
 15. The method of claim 12, further comprising communicating, foreach media path, the input propagation delay from the edge input deviceto the edge output device.
 16. The method of claim 12, furthercomprising communicating, for each media path, the input propagationdelay from the edge input device to the edge output device in parallelwith the related media signal that is transported along the media path.17. The method of claim 12, further comprising communicating anaccumulated propagation delay for each related media signal andassociated media path to the edge output device of the media path. 18.The method of claim 17, wherein the determining the uncorrectedpropagation delay for each media path includes determining theuncorrected propagation delay based on the accumulated propagationdelay.
 19. The method of claim 11, wherein the delaying includes timealigning all of the related media signals to within 20 ms.
 20. Themethod of claim 11, wherein the delaying includes time aligning allaudio media signals of the related media signals to within 2 ms.
 21. Amedia transport system, comprising: a first media path that includes afirst edge input device at a first ingress and a first edge outputdevice at a first egress, wherein the first edge input device isconfigured to receive a first media signal from a shared source space,wherein the first edge output device is configured to receive the firstmedia signal from the first edge input device and to receive a firstupstream delay signal from the first edge input device, wherein thefirst edge output device is configured to determine a first uncorrectedpropagation delay from the first ingress to the first egress based uponthe first upstream delay signal; and a second media path that includes asecond edge input device at a second ingress and a second edge outputdevice at a second egress, wherein the second edge input device isconfigured to receive a second media signal from the shared sourcespace, wherein the second edge output device is configured to receivethe second media signal from the second edge input device and to receivea second upstream delay signal from the second edge input device,wherein the second edge output device is configured to determine asecond uncorrected propagation delay from the second ingress to thesecond egress based upon the second upstream delay signal; wherein thefirst edge output device and the second edge output device areconfigured to settle on a target propagation delay that is at least aslarge as a maximum of the first uncorrected propagation delay and thesecond uncorrected propagation delay.
 22. The media transport system ofclaim 21, wherein the media transport system includes a network fabricto interconnect the first media path from the first edge input device tothe first edge output device and to interconnect the second media pathfrom the second edge input device to the second edge output device. 23.The media transport system of claim 21, wherein the first media pathincludes a first dynamic delay element configured to delay the firstmedia signal based upon a first delay command, wherein the second mediapath includes a second dynamic delay element configured to delay thesecond media signal based upon a second delay command wherein the firstedge output device is configured to command the first dynamic delayelement to delay the first media signal by a difference between thetarget propagation delay and the first uncorrected propagation delay,and wherein the second edge output device is configured to command thesecond dynamic delay element to delay the second media signal by adifference between the target propagation delay and the seconduncorrected propagation delay.
 24. The media transport system of claim23, wherein the first edge output device is configured to command thefirst dynamic delay element to delay the first media signal an amount ofdelay related to a value by which the second uncorrected propagationdelay exceeds the first uncorrected propagation delay, and wherein thesecond edge output device is configured to command the second dynamicdelay element to delay the second media signal an amount of delayrelated to a value by which the first uncorrected propagation delayexceeds the second uncorrected propagation delay.
 25. The mediatransport system of claim 21, wherein the first edge output device andthe second edge output device are configured to exchange the firstuncorrected propagation delay and the second uncorrected propagationdelay, and wherein each of the first edge output device and the secondedge output device is configured to determine the maximum of the firstuncorrected propagation delay and the second uncorrected propagationdelay as the target propagation delay.
 26. The media transport system ofclaim 21, wherein the first edge output device is configured to receivethe second uncorrected propagation delay from the second edge outputdevice, wherein the first edge output device is configured to determinethe maximum of the first uncorrected propagation delay and the seconduncorrected propagation delay as the target propagation delay, andwherein the first edge output device is configured to send the targetpropagation delay to the second edge output device.
 27. The mediatransport system of claim 21, wherein the media transport systemincludes a plurality of ingresses and a plurality of egresses, isconfigured to receive a plurality of related media signals from theshared source space at the plurality of ingresses, and is configured totransmit the plurality of media signals to the shared observation spacefrom the plurality of egresses; wherein the plurality of ingressesincludes the first ingress and the second ingress, wherein the pluralityof egresses includes the first egress and the second egress, and whereinthe plurality of media signals includes the first media signal and thesecond media signal; and wherein each of the plurality of media signalshas an uncorrected propagation delay and wherein the target propagationdelay is a maximum of the uncorrected propagation delays of theplurality of media signals.
 28. The media transport system of claim 21,wherein the first edge input device and the second edge input device areconfigured to transmit the first media signal from the first egress andto transmit the second media signal from the second egress with arelative propagation delay of less than 20 ms.